Ever since connecting my plex server to my brother's Sonos account as a music source (May 2021) I always have the option of casting to my brother's speakers from my plex mobile apps and from the web interface at app.plex.tv
I have tried removing all Sonos references from Authorized Devices in plex settings. My brother has removed my plex server music from his Sonos app. He's even gone so far as changing his Sonos password. Regardless, I am still able to cast music to his speakers.
I have my own Sonos account and can play my plex server music on my Sonos products via the Sonos app. However, from my plex apps the only Sonos casting options I can see are my brother's speakers.
I can have my plex server authorized as a data source on multiple Sonos accounts; both accounts can play plex content on their individual systems. However, in my case it seems Plex apps themselves can only cast to the system of a single Sonos account. I don't know from where this limitation originates. It's as if my brother's Sonos has granted a permanent security token to my plex account and I cannot seem to get free of it to cast to my own Sonos system.
Does anyone have an suggestions to get my plex account free of my brother's Sonos account? Why am I able to cast to my brother's system after he's changed his password?